| Description |
Stunning observations with SPIRE FTS of Mrk 231 have shown that CO lines are very bright up to J=13-12, and there is no sign of a decline in the CO Spectral Line Energy Distribution (SLED). Our SPIRE FTS spectra show that this is a common feature of AGN type galaxies. Therefore, we propose to observe a set of 4 very high-J CO line transitions using the PACS spectrometer, for 5 of these well studied proto-typical (Ultra-)Luminous Infrared Galaxies ((U)LIRGs) and one starburst galaxy. The question of the relative role and contribution of AGN to the far-infrared luminosities of local (U)LIRG systems has long been a problem in our understanding of the evolutionary path of these objects, and as well for the interpretation of deep far-infrared surveys.Our SPIRE FTS and our ground-based CO line observations together with the PACS observations in this program will allow us, for the first time, to complete a full CO SLED for a set of (U)LIRGs. Combining this with our models of Photon Dominated Regions (PDRs) and X-ray Dominated Regions (XDRs), we will then be able to determine the physical state of the interstellar medium and estimate the starburst/AGN contribution to the total energetics of these systems. |
